linux-cve-announce - CVE-2024-56762: io_uring/sqpoll: fix sqpoll error handling races

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Message-ID: <2025010654-CVE-2024-56762-9a9f@gregkh>
Date: Mon,  6 Jan 2025 17:20:56 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56762: io_uring/sqpoll: fix sqpoll error handling races

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

io_uring/sqpoll: fix sqpoll error handling races

BUG: KASAN: slab-use-after-free in __lock_acquire+0x370b/0x4a10 kernel/locking/lockdep.c:5089
Call Trace:
<TASK>
...
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
try_to_wake_up+0xb5/0x23c0 kernel/sched/core.c:4205
io_sq_thread_park+0xac/0xe0 io_uring/sqpoll.c:55
io_sq_thread_finish+0x6b/0x310 io_uring/sqpoll.c:96
io_sq_offload_create+0x162/0x11d0 io_uring/sqpoll.c:497
io_uring_create io_uring/io_uring.c:3724 [inline]
io_uring_setup+0x1728/0x3230 io_uring/io_uring.c:3806
...

Kun Hu reports that the SQPOLL creating error path has UAF, which
happens if io_uring_alloc_task_context() fails and then io_sq_thread()
manages to run and complete before the rest of error handling code,
which means io_sq_thread_finish() is looking at already killed task.

Note that this is mostly theoretical, requiring fault injection on
the allocation side to trigger in practice.

The Linux kernel CVE team has assigned CVE-2024-56762 to this issue.

Affected and fixed versions
===========================

	Fixed in 6.1.123 with commit 6237331361711810d8f2e3fbfe2f7a6f9548f5e0
	Fixed in 6.6.69 with commit 80120bb4eef7848d5aa3b1a0cd88367cd05fbe03
	Fixed in 6.12.8 with commit 8e8494c83cf73168118587e9567e4f7e50ce4fd8
	Fixed in 6.13-rc5 with commit e33ac68e5e21ec1292490dfe061e75c0dbdd3bd4

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-56762
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	io_uring/sqpoll.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/6237331361711810d8f2e3fbfe2f7a6f9548f5e0
	https://git.kernel.org/stable/c/80120bb4eef7848d5aa3b1a0cd88367cd05fbe03
	https://git.kernel.org/stable/c/8e8494c83cf73168118587e9567e4f7e50ce4fd8
	https://git.kernel.org/stable/c/e33ac68e5e21ec1292490dfe061e75c0dbdd3bd4